Typically, vans, RVs (Recreational Vehicles), and SUVs (Sport Utility Vehicles) are provided with at least two rows of seats. The second row of the seats is typically furnished with a fold-flat feature that allows the seatback thereof to be folded backward to a flat position substantially parallel to a seat cushion.
However, in such a conventional seat, both sides of the second row seatback come into an interference with a trim of a wheel housing as the seatback is folded into a flat position. This is because the trim of the wheel housing protrudes into the interior of the vehicle. For prevention such interference, some seats employ divided seatbacks consisting of a main seatback and a subsidiary seatback. In these designs, the subsidiary seatback is positioned at one side of the main seatback, where the interference with the wheel housing occurs, and fits into the main seatback. When the seatback is folded into a flat position, the subsidiary seatback is removed from the main seatback so as to prevent interference with the trim of the wheel housing. However, in such seats, it is troublesome to remove or attach the subsidiary seatback from or to the main seatback whenever the fold-flat feature is desired.
In another conventional seat, divided seatbacks consisting of a main seatback and a subsidiary seatback are provided. The subsidiary seatback is hinged to the main seatback. In an upright position, the subsidiary seatback is positioned in a line with the maim seatback. With such an arrangement, the subsidiary seatback is folded toward a center of the main seatback, so that the interference with the trim of the wheel housing is prevented. However, this seatback is disadvantageous in that the folded subsidiary seatback constrains movement of a passenger, thereby, making the passenger feel uncomfortable.